The present invention relates to means for disintegrating unconsolidated overburden, and more particularly to apparatus for comminuting and slurrying overburden, and transporting it to a remote site.
Certain types of valuable mineral deposits occur over a broad area, a short distance beneath the soil surface. Access to the minerals may be had by removing the overburden which overlies the minerals, a process known as stripping. When the overburden material is consolidated (e.g. rock or shale) it must be broken into discrete chunks and carried away. Procedures such as drilling and blasting are required to break up and to dislodge such consolidated overburden.
Where the overburden is unconsolidated (e.g. clay, sand, topsoil and the like) the removal operation is simpler. Shovels, draglines, tractors and loaders may be used to dislodge the overburden. The material is then dumped into trucks or other conveyances and transported to a depositing area for dumping. While this method is usually satisfactory it is relatively expensive in that a number of vehicles are required, and a great deal of fuel is consumed in the operation of the vehicles. Further, simply dumping the dislodged overburden creates vast areas of soft, loose material which requires subsequent compaction if a firm surface is desired. A still more serious problem is that the use of vehicles to transport the overburden causes stripping operations to be dependent upon the weather. Rains soften the ground surface making it impossible for the transport and digging vehicles to operate. In such cases, strippng operations must be suspended until the soil has dried sufficiently to allow the vehicles to be used.
The principle of transporting comminuted, slurried material has long been known. Practical applications of this procedure, however, have heretofore been confined to situations in which the material to be transported is of a predictable, uniform nature. Usually the material has taken the form of fine powdered or granular materials such as clinkers or ashes. For example, in U.S. Pat. No. 2,980,944 -- Foresman a slurrying system is disposed beneath the stoker discharge of a furnace. The material discharged from the stoker falls into a chamber therebeneath where it is agitated and circulated by means of water jets. Most of the material is washed horizontally through a vertically-extending screen. Coarse particles which do not pass through the screen settle into an area above a pair of grinding rolls, which comminute them and pass them to a discharge pipe.
Similarly, in U.S. Pat. No. 1,818,967 -- Allen a scheme for slurrying furnace discharge is shown in which a spray of water is directed upon ash which has been allowed to fall upon an inclined floor section. The exposed surface of the ash pile is washed away by the water, through a grate and into a discharge conduit.
These apparatus, however, are unsuitable for use with stripping operations wherein non-uniform, unconsolidated overburden is encountered. It has been found that apparatus of the type shown by Foresman may readily clog in such an environment, and does not produce the desired slurry. Apparatus like that taught by Allen is also not well adapted to receive and transport materials of varying sizes and characteristics. Accordingly, it will be understood that a long-standing need has existed for an improved apparatus for receiving, slurrying and transporting unconsolidated overburden.
It is therefore an object of the present invention to provide improved means for disintegrating materials to be slurried and transported.
It is another object of the invention to provide apparatus for disintegrating and slurrying unconsolidated overburden.
Still another object is to provide improved means for slurrying and transporting unconsolidated overburden to a remote site.